Basic knowledge of PHP - complete collection of PHP functions

This article sorts out some commonly used functions , And classified . If it helps you , Yes , Bloggers are very blunt to Three even

One 、 Array function

#1.  Array creation 
	array(); #  Generate an empty array  

    array_combine($x, $y); #  Generating arrays ,  use  $x  The value of the array is used as the   Key name , $y  The value of the array is the value of the new array   value 

#2.  Array merging and splitting 
    array_merge($x, $y, $z); #  Array merge 

    array_slice($array, $start, $length); #  Custom location interception 

#3.  Array comparison 
    array_diff($x, $y, $z); #  Return difference set 

    array_intersect($x, $y, $z); #  Return to intersection 

#4.  Find and replace arrays 
    array_search($search, $array); #  Find value ,  There is a return key , There is no return  false

    array_splice($search, $start, $length, $new); #  from  $search  Remove from array ,  And use  $new  Chinese and new elements replace 

    array_sum(); #  Returns the sum of all the values in the array 

    array_key_exists($key, $array); #  Check  $key  Whether the key name of is  $array  in 

    in_array($val, $array); #  Check  $val  Is the value of  $array  in 

#5.  Array key operation 
    count(); #  Get the number of elements in the array 

    array_unique(); #  Array value de duplication , Delete duplicate elements , Returns the remaining array 

    array_rand($array, $length); #  Randomly extract from an array  $length  Elements ,  Be careful :  The return is   Key name 

    array_keys(); #  Put all the keys in the array , Make a new array 

    array_values(); #  All the values in the array , Make a new array 

    array_flip(); #  Invert the keys and values of the array 

    array_reverse(); #  Return the array of flipping order 

    array_count_values(); #  Count the number of occurrences of all values in the array  ['A'=>3, 'B'=>4]

    shuffle($array); #  Scramble the elements in the array , Rearrange randomly 

#6.  Array pointer operation 
	key(); #  Returns the key name of the current element of the internal pointer of the array 
	
	current(); #  Returns the value of the current element of the internal pointer of the array 

	next(); #  Move the pointer to the current element back one bit , And return the value of the element moved back 

	prev(); #  Move the pointer to the current element forward one bit , And return the value of the element moved forward 

	end(); #  Point the array pointer to the last element , And return the value of the element 

	reset(); #  Point the array pointer to the first element , And return the value of the element 

	array_shift(); #  Delete the first element in the array , And return the value of the deleted element 

	array_unshift($array, $value); #  Insert one or more elements at the beginning of the array 

	array_pop(); #  Delete the last element in the array .

	array_push($array, $value); # #  Insert one or more elements at the end of the array 

	list(); #  Assign values to a group of variables using elements in an array   example : list($a, $b, $c) = ['a', 'b', 'c'];

#7.  Array sorting 
	sort(); #  Sort the values of the array in ascending order , Do not keep the original key name 

	rsort(); #  Sort the values of the array in descending order , Do not keep the original key name 

	asort(); #  Sort the values of the array in ascending order , Keep the original key name 

	arsort(); #  Sort the values of the array in descending order , Keep the original key name 

	ksort(); #  Sort the keys of the array in ascending order , Keep the original key name 
	
	krsort(); #  Sort the keys of the array in descending order , Keep the original key name 

	natsort(); #  Use natural order algorithm to sort the values in the array , Keep the original key name 

	natcasesort(); #  Use natural order algorithm to sort the values in the array , Keep the original key name , The function is case insensitive 

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Two 、 Mathematical functions

abs(); #  Returns the absolute value of a number  3.2

ceil(); #  Rounding up 

floor(); #  Rounding down 

fmod(5.4, 1.3); #  Floating point remainder  0.2

max(3, 1, 5, 7); #  Maximum  7

min(4, 2, 6, 8); #  minimum value  2

mt_rand(1, 10); #  My random value this time is  382819

pow(x, y); #  return  x  Of  y  Power   example : pow(2,2);  Output  4

pi(); #  Get the pI value ,  The precision of the return value is determined by  php.ini  Medium  precision  Command control , 3.1415926535898

round(); #  Floating point rounding 

sqrt(16); #  Returns the square root of a number  4

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3、 ... and 、 Character functions

# 1.  String statistics 
	strlen(); #  Statistical string length ,  Chinese accounts for  3  Bytes 

	mb_strlen(); #  Statistical string length ,  Chinese accounts for  1  Bytes 

	str_word_count($string, $format, $characters); #  Count the number of words in the string ,  Please refer to the manual for more usage 


# 2.  String search and replacement 
	str_replace($new, $old, $string); #  String substitution operation ,  Case sensitive 

	str_ireplace($new, $old, $string); #  String substitution operation ,  Case insensitive 

	substr_replace($string, $replace, $start, $length); #  Replace one part with another string 
	
	substr_count($string, $search); #  Count the number of times one string appears in another string 
	
	similar_text($string1, $string2, $percent); #  Returns two strings with the same number of strings or the same percentage value 

	strstr($string, $search, $before=false); #  Find where a string first appears in another string , And returns all characters from this position to the end of the string or the beginning of the string ,  No return  FALSE,  Case sensitive 

	stristr($string, $search, $before=false); #  Find where a string first appears in another string , And returns all characters from this position to the end of the string or the beginning of the string ,  No return  FALSE,  Case insensitive 

	strchr($string, $search, $before=false); # strstr();  Another name for 

	strrchr($string, $search); #  Find the last occurrence of a string in another string , And returns all the characters from that position to the end of the string ,  No return  FALSE,  Case sensitive 
	
	strpos($string, $search, $start); #  Returns the position where the string first appears in another string ,  Case sensitive 

	stripos($string, $search, $start); #  Returns the position where the string first appears in another string ,  Case insensitive 

	strrpos($string, $search, $start); #  Returns the last occurrence of a string in another string ,  Case sensitive 

	strripos($string, $search, $start); #  Returns the last occurrence of a string in another string ,  Case insensitive 

	strspn($string, $charlist, $start, $length); #  Back in the  $string  Contained in the  $charlist  The number of characters specified in the parameter .

	strcspan($string, $char, $start, $length); #  The function returns before any specified character is found , The number of characters to find in the string （ Including Spaces ）.


# 3.  Character segmentation and splicing 
	explode($separator, $string); #  Press  $separator  Separate  $string ,  Break it up and reassemble it into an array 
	
	implode($separator, $array); #  use  $separator  Separate each value in the array ,  Convert to new string 

	substr($string, $start, $length); #  Chinese accounts for  3  Bytes ,  stay  $string  In a string ,  from  $start  Position start ,  return  $length  Length string , $length  Default until the end of the string 

	mb_substr($string, $start, $length); #  Chinese accounts for  1  Bytes ,  stay  $string  In a string ,  from  $start  Position start ,  return  $length  Length string , $length  Default until the end of the string  

	chunk_split($string, $length, $separator); #  Press the string  $length  The length is divided into small pieces ,  With  $separator  Separate ,  Returns the new string 

	str_split($string, $length); #  Press the string  $length  The length is divided into small pieces ,  Returns an array of 

# 4.  String comparison  ( The two strings are the same and return  0)
	strcmp($string1, $string2); #  Compare two strings ,  Case sensitive 

	strcasecmp($string1, $string2); #  Compare two strings ,  Case insensitive 

	strncmp($string1, $string2, $length); #  Before comparing two strings  $length  length ,  Case sensitive 

	strncasecmp($string1, $string2, $length); #  Before comparing two strings  $length  length ,  Case insensitive 

	strnatcmp($string1, $string2); #  Use " natural " Algorithm to compare two strings ,  Case sensitive 

	strnatcmp($string1, $string2); #  Use " natural " Algorithm to compare two strings ,  Case insensitive 


# 5.  toggle case 
	strtolower($string); #  All strings are converted to lowercase 

	strtoupper($string); #  All strings are capitalized 

	lcfirst($string); #  The first letter of the string is lowercase 

	ucfirst($string); #  The initial of a string is uppercase 

	ucwords($string); #  String the first letter of each word is capitalized 


# 6.  Generation and transformation 
	strrev(); #  Reverse string 
	
	str_repeat($string, $multiplier); #  Duplicate string  $multiplier  Time 

	str_pad($string, $length, $pad_string, $pad_type); #  Fill the string with the specified length , $pad_string  Characters to be filled , $pad_type  For the type  (STR_PAD_RIGHT:  Fill right ( Default ) STR_PAD_LEFT:  Fill left  STR_PAD_BOTH:  Fill both sides )

	wordwrap($string, $length); #  Wrap the string by the specified length 

	str_shuffle(); #  Randomly scrambling strings 

	number_format(); #  Thousands of formatted numbers 

	parse_str(); #  Parse the string into variables   example : parse_str("name=Chon&height=175");

	trim($string, $char); #  Remove at the beginning and end  $char  character , $char  Default is space 

	ltrim($string, $char) #  Remove the at the beginning  $char  character , $char  Default is space 
        
    rtrim($string, $char) #  Remove the at the end  $char  character , $char  Default is space 
        

# 7. html  Tag associated functions 
    htmlentities(); #  Convert a character to  html  Entity 

	html_entity_decode(); #  hold  html  Entity to character 

	htmlspecialchars(); #  Predefined characters (<>'"&) turn  html  Entity 

	htmlspecialchars_decode(); #  Predefine  html  Entity (&amp; &quot; ' &lt; &gt;)  To a character 

	nl2br(); # \n  To  <br>  label 
	
	strip_tags(); #  Remove... From the string  html  label 

	addslashes(); #  Specify predefined characters (<>'"&) Add backslash before 

	stripslashes(); #  Delete from  addslashes()  Added backslash 

	addcslashes($string, $char); #  stay  $string  In a string ,  stay  $char  Add a backslash before the specified character of 

	stripcslashes(); #  Delete from  addcslashes()  Added backslash 

	quotemeta(); #  Predefined characters in the string (.\+*?[]^$()) Add backslash before 

	chr(); #  Back to different  ASCII  Value character 

	ord(); #  Returns the of the first character in a string  ASCII  value 

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Four 、 File functions

#  Open a file or  URL,  See the manual for more : https://www.php.net/manual/en/function.fopen
fopen($filename, $mode, $include_path, $context);

$mode Is access type , The following are possible values

“r” （ Read only open , Point the file pointer to the file header ）
“r+” （ Read write mode on , Point the file pointer to the file header ）
“w” （ Write mode on , Clear the contents of the file , If the file does not exist, try to create it ）
“w+” （ Read write mode on , Clear the contents of the file , If the file does not exist, try to create it ）
“a” （ Write mode on , Write the file pointer to the end of the file , If the file does not exist, try to create it ）
“a+” （ Read write mode on , Save the contents of the file by writing the file pointer to the end of the file ）
“x” （ Create a new file and open it in write mode , Returns... If the file already exists FALSE And a mistake ）
“x+” （ Create a new file and open it read-write , Returns... If the file already exists FALSE And a mistake ）

fclose(); #  Close open file pointer 

#  File attribute 
	clearstatcache(); #  Eliminate the cache of running results 

	file_exists(); #  Check if the file or directory exists 
	
	filesize(); #  Get file size 

	filectime(); #  Get file creation time 

	filemtime(); #  Get file modification time 

	fileatime(); #  Get the last access time of the file 

	is_readable(); #  Check that the file is readable 

	is_writable(); #  Check that the file is writable 

	is_executable(); #  Check if the file is executable 

	is_file(); #  Check whether the file is a regular file 

	stat(); #  Get most of the information in the file   See the manual for details : https://www.php.net/manual/en/function.stat

#  File operations 
	file_get_contents(); #  Read the entire file into a string 

	file_put_contents($file, $data, $mode); #  Write a string to a file 

	fwrite($filename, $string, $length); #  take  $string  write file , $length  Is the maximum number of bytes written 

	fread($filename, $length); #  Read open files , $length  Is the maximum number of bytes read 

	feof(); #  Check whether the file pointer is the end position 

	fgets(); #  Read a line from the pointer of the file and return 

	fgetc(); #  Reading a single character from the pointer of the file returns 

	file(); #  Read the contents of the file into an array 

	readfile(); #  Read a file , Write the contents of the file to the output buffer .

	ftell(); #  Returns the current position of the file pointer 

	fseek($file, $offset); #  Locate the file pointer to a certain location 

	rewind(); #  Point the file pointer to the beginning of the file 

	flock($file, $lock); #  Lock or release files 

#  File upload download 
	is_uploaded_file(); #  Judge whether the document is passed  HTTP POST  Upload 
	
	move_uploaded_file(); #  Move the uploaded file to a new location 

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5、 ... and 、 Directory functions

basename($path, $suffix); #  Return the filename part of the path ,  If specified  $suffix ,  The extension... Is not displayed 

dirname(); #  Return the directory part of the path 

pathinfo(); #  Return the file path information 

mkdir(); #  new directory 

rmdir(); #  Delete directory 

unlink(); #  Delete file 

copy($file, $to_file); #  Copy files 

rename($oldname, $newname); #  Rename a file or directory 

opendir(); #  Open directory handle 

readdir(); #  Read entries from the directory handle 

closedir(); #  Close directory handle 

rewinddir(); #  Rewind directory handle 

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6、 ... and 、 Time function

date_default_timezone_set("Asia/Shanghai"); #  Set the default time zone ,  Time zone table link : https://www.php.net/manual/en/timezones.php

date_default_timezone_get(); #  Get the default time value 

time(); #  Returns the current  Unix  Time stamp 

microtime(); #  Returns the current  Unix  The microseconds of the timestamp 

date($format, $timestamp); #  Format a local time / date   example : date("Y-m-d H:i:s", time());

getdate($timestamp); #  Returns information about the time and date of the timestamp ,  The format is associative array 

strtotime(); #  Parse string to  Unix  Time stamp 

# strtotime  Case study 
strtotime('now');

strtotime('+1 day');

strtotime('+1 week 2 days 3 hours 4 seconds');

strtotime('next Monday');

strtotime('last Monday');